Heat-insulating panel serving as concrete form and method of manufacturing the same

ABSTRACT

The present invention relates to a heat-insulating panel formed of curly contracted pieces of tapes, for example thermally contracted pieces of magnetic tapes, and a method of manufacturing such a panel. In particular, the present invention concerns a heat-insulating panel which also serves as a concrete form. The heat-insulating panel has excellent strength characteristics such, as bending strength and bending rigidity, and dimensional stability, as well as characteristics of sound absorption, heat-insulation, electrostatic shielding and electromagnetic wave absorption, and is usable for a concrete form when placing concrete during the construction of a building formed of reinforced concrete or steelframe reinforced concrete. The present invention relates also to a method of manufacturing the panel.

This is a divisional of application Ser. No. 08/331,715, filed on Oct.31, 1994, now U.S. Pat. No. 5,631,075.

FIELD OF THE INVENTION AND RELATED ART STATEMENT

The present invention relates to a heat-insulating panel formed of curlycontracted pieces of tapes, for example thermally contracted pieces ofmagnetic tapes, and a method of manufacturing such a panel. Inparticular, the present invention concerns a heat-insulating panel whichalso serves as a concrete form. The heat-insulating panel has excellentstrength characteristics such, as bending strength and bending rigidity,and dimensional stability, as well as characteristics of soundabsorption, heat-insulation, electrostatic shielding and electromagneticwave absorption, and is usable for a concrete form when placing concreteduring the construction of a building formed of reinforced concrete orsteelframe reinforced concrete. The present invention relates also to amethod of manufacturing the panel.

Conventionally, to improve the heat-insulation of a building formed ofreinforced concrete or steelframe reinforced concrete for energysavings, a construction method has been utilized wherein heat-insulatingpanels using synthetic resin foams are directly attached to concretewall surfaces.

The heat-insulating panel using a synthetic resin foam, however, doesnot have sufficient strength and cannot withstand the side pressure ofconcrete by itself when placing concrete, so that it must be attached tothe inside of a supporting member, that is, a concrete frame such as aframe plywood, complicating the construction process. It furtherpresents the following disadvantages: namely, the fixing between theframe and the heat-insulating panel is insufficient; when theheat-insulating panel is deformed due to the side pressure of concreteand thermal stress, concrete leaks into a space between the frame andthe heat-insulating panel and the heat-insulation capabilitydeteriorates; and after removal of the frame, the heat-insulating panelcannot ensure the smooth surface.

To eliminate the above disadvantages, a heat-insulating panel serving asa frame, for example in Japanese Patent KOKOKU Publication No. 5-47696(1993), wherein a panel is reinforced by sticking a face plate on thesurface of a synthetic resin foam so as to improve bendingcharacteristics, and the panel itself can be used as a frame for placingconcrete.

OBJECT AND SUMMARY OF THE INVENTION

However, when such a heat-insulating panel is used as a concrete framewhen placing concrete during building construction using reinforcedconcrete or steelframe reinforced concrete, it has the followingdisadvantages:

To withstand the side pressure of uncured or unhardened concrete, theheat-insulating panel serving as a frame must have good bendingcharacteristics and dimensional stability. Specifically, the panel hasto have a bending strength of 50 kgf/cm² or more, and a bending rigidityof 4.0×10⁵ kgf·cm². Furthermore, only 3 mm or less of the deflection ofthe frame surface is permitted between longitudinal battens upon placingunhardened concrete. Accordingly, the heat-insulating panel of this typehas to have a face plate of a relatively high quality or a multi-layerface plate, resulting in increased costs. Moreover, the synthetic resinfoam constituting a main member of the panel shows limitations in thecompression strength and bearing strength. Accordingly, when the panelis used as a frame, the battens for supporting the frame may become sunkinto the panel during construction.

In Japanese Patent Provisional Publication No. 6-198649 (1994), a methodof manufacturing a building material board is proposed, which includesthe steps of cutting or shredding waste magnetic tapes such as videotapes or cassette tapes in suitable lengths and heating them; and addinga binder to the cut or shredded pieces of tapes and compression-moldingthem.

When the building material board thus obtained is used as a frame, itbecomes greatly deflected upon placing concrete because of its lowbending rigidity.

An object of the present invention is to provide a heat-insulating panelwhich can be used as a frame for concrete placing and which hassufficient bending characteristics required for the frame and anexcellent dimensional stability.

To solve the above-described problems, the present inventors havecarried out extensive research on frames and panels and have found a newheat-insulating panel serving also as a concrete frame, which isobtained by compression-molding 100 parts by weight of curly contractedpieces of tapes added with 10 to 50 parts by weight of thermosettingresin as a binder, wherein the curly contracted pieces of tapes areobtained by heating of cut or shredded pieces of magnetic tapes havinglengths of 20 mm or less; and a method of manufacturing the panel.

The above tape is not particularly limited insofar as being curlycontracted, and may include a magnetic tape, such as a video tape orcassette tape. The cut pieces or shredded pieces of magnetic tapespreferably contain those having lengths from 5 to 20 mm in an amount of50% or more on the basis of the total weight of the tapes. The abovethermosetting resin is preferably at least one kind selected from agroup consisting of phenol resin, urea resin, polyester resin,polyurethane resin, epoxy resin, and melamine resin.

Specifically, magnetic tapes, such as video tapes or cassette tapes, arecut or shredded into lengths of 20 mm or less, and heated at 100° to200° C. to be curly contracted. The curly contracted pieces of magnetictapes are then mixed with a binder of thermosetting resin andcompression-molded under a pressure from 2 to 20 kgf/cm² and at atemperature from 100° to 200° C. Thus, a heat-insulating panel whichalso serves as a concrete frame and which has a bending strength of 50kgf/cm² or more (the bending test using a particle board in accordancewith JIS A 5908), a bending rigidity of 4×10⁵ kgf·cm² or more, and themaximum deflection of 2 mm or less upon placing concrete. Moreover, thepanel has characteristics of electromagnetic wave absorption andelectrostatic shielding in addition to characteristics of soundabsorption and heat-insulation. The above magnetic tapes may also beused in such a manner that part of tapes are not contracted into curledshapes and are left as being cut or shredded.

The tape is not limited in kind as described above, and may include avinyl film, polyethylene film, polypropylene film, and cellulose film.

If magnetic tapes such as video tapes or cassette tapes are used, theyare cut or shredded in lengths of 20 mm or less, preferably, 10 mm orless before heating; and they contain those having lengths from 5 to 20mm in an amount of 50% or more, preferably 70% or more, on the basis ofthe total weight of tapes. When the length of each magnetic tape is morethan 20 mm, the surface condition of the compression-molded tapesbecomes coarse, and the strength required for a frame is reduced, makingits practical use more difficult to find. When the cut pieces orshredded pieces contain those having lengths from 5 to 20 mm in anamount of less than 50% on the basis of the total weight of tapes, thetapes themselves cannot reinforce the bending strength sufficiently,thus making it difficult to obtain the strength characteristics requiredfor a frame.

As the above binder, a material capable of being hardened and molded byheating, such as phenol resin, urea resin, polyester resin, polyurethaneresin, epoxy resin or melamine resin, may be used. Each resin may beused in the form of powder or emulsion.

The above binder is added to 100 parts by weight of tapes, such asmagnetic tapes, in an amount of 10 to 50 parts by weight, preferably, 15to 30 parts by weight. When the amount of the binder is less than 10parts by weight, the bonding force between tapes are not sufficient, andthe strength characteristics required for a frame cannot be obtained.When it is more than 50 parts by weight, the strength becomes saturated,and further increases in the amount of the binder would simply result inincreased costs.

The heat-insulating panel of the present invention is manufacturedaccording to the following procedure:

Magnetic tapes, such as video tapes or cassette tapes, are cut orshredded in lengths of 20 mm or less, preferably, 3 to 10 mm, and heatedat 100° to 200° C., preferably 140° to 170° C. to become contracted intocurled shapes. The contracted tapes are mixed with a binder andcompression-molded while being heated.

The heating temperature during the heat treatment is preferably in therange from 100° to 200° C. At a temperature of less than 100° C., thetapes may not contract into curly shapes. At a temperature more than200° C., the tapes are deteriorated by oxidization and cannot be used asa panel.

The heating temperature during compression-molding should also be in therange from 100° to 200° C. At a temperature less than 100° C., thebinder is not thermally hardened and does not allow the tapes to becompression-molded. At a temperature more than 200° C., the tapes aredeteriorated by oxidization and cannot be used as a panel component.

As for the compression-molding pressure, if it is less than 2 kgf/cm²,the tapes cannot be compression-molded into a panel. If it is more than20 kgf/cm², the density of the panel may become too large to obtain agood heat-insulating capability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are perspective views each showing the shape of acontracted piece of a tape; and

FIG. 2 is a perspective view of a cut piece of a heat-insulating panelserving as a concrete frame according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1A shows a contracted piece (a) formed in a spiral shape; and FIG.1B is a curled contracted piece (b) of a tape which is C-shaped insection. Contracted pieces having various shapes may be used, other thanthe above pieces (a) and (b). However, either of these shapes isdesirable to have a hollow portion C at the whole or part of theinterior thereof.

FIG. 2 shows the cut piece of a heat-insulating panel obtained by amethod wherein the curled contracted pieces of tapes are added with abinder, and then heated and compression-molded. At this time, simply cutpieces or shredded pieces of tapes may be added in a suitable amount. Anactual panel is formed in a size of, for example, 5-25 mm(thickness)×400-1000 mm (length)×400-1000 mm (width).

In FIG. 2, reference numeral 1 designates a heat-insulating panelserving as a concrete frame; 2 contracted pieces of tapes bonded to eachother by means of a binder; and 3 a nonwoven fabric stuck on the surfaceof the panel 1, which fabric is as thin as 0.1 to 0.001 mm.

When the above panel 1 is formed, ferrite, carbon black and conductivemetal powder may be added together with the binder; or conductive metalfibers or metal meshes may be sandwiched in the panel 1.

According to the present invention, by adding the above binder to theabove shredded tapes and compression-molding them, air is entrapped inthe curly contracted pieces of tapes and spaces are formed insidethereof. Thus, there can be obtained a heat-insulating panel serving asa concrete frame having characteristics of electrostatic shielding andelectromagnetic absorption in addition to characteristics of soundabsorption and heat-insulation.

The panel of the present invention is used as a concrete frame forplacing concrete. After the placed concrete is hardened, the panel isused as a wall material, ceiling member or floor member of a building inassociation with a concrete support 4, as shown in FIG. 2. In addition,the panel of the present invention may also be used alone without anyconcrete support.

EXAMPLE

In this example, the following materials were used.

Magnetic tape: Video tape sold by FUJI PHOTO FILM K.K.

Video tape sold by TDK K.K.

Urea resin: Urea resin MD-440 sold by DAINIPPON INK KOGYO.K.K.

Phenol resin: Phenol resin PR-311 sold by SUMITOMO DUREZ COMPANY, LTD.

Concrete to be placed:

Plain concrete manufactured by ASANO CONCRETE CO., LTD.

Slump: 21 cm

Nominal strength: 210 kgf/cm²

Coarse aggregate maximum size: 20 mm

First, the tapes were shredded into scale shapes having lengths of 5 mmor less by a shredder sold by TURBO KOGYO COMPANY, LTD under the tradename of TURBO-CUTTER. The shredded pieces of tapes were heated in anelectric furnace for 3 min at 155°±5° C. while being agitated, thusforming curly contracted pieces of tapes. The curly contracted pieces oftapes as a raw material were mixed with a binder of the above-describedresin, and were uniformly mixed in a Henschel mixer. The mixture was putin a transfer type mold, and was compression-molded by a hot-press underthe condition of 150°×10 min.

The panel thus obtained had a size of 1800×900 mm and a specific gravityof 0.4.

A test piece having a size of 200×50 mm was subjected to a centralizedload test (bending span: 150 mm) in accordance with a bending strengthtest for particle boards (JIS A 5908).

The bending rigidity was obtained by calculating Young's modulus fromthe relationship between the load and the deflection in the abovebending strength test, and multiplying the value by the second moment ofarea.

The concrete placing test was performed using a wall having a height of3600 mm and a thickness of 200 mm. The concrete placing rate was set at20 m/h. The maximum deflection was obtained by measuring the deflectionat the center of a gap between longitudinal battens by means of electriccalipers, and obtaining the maximum value from the measured values.

    __________________________________________________________________________    Inventive and                                                                 Comparative                                                                   Examples                                                                              Inv. Ex. 1                                                                          Inv. Ex. 2                                                                          Inv. Ex. 3                                                                          Inv. Ex. 4                                                                          Inv. Ex. 5                                                                          Inv. Ex. 6                              __________________________________________________________________________    mixing ratio                                                                  magnetic tape                                                                 length of tape                                                                        50 parts by weight      70 parts by weight                            (5-20 mm                                                                      length of tape                                                                        50 parts by weight      30 parts by weight                            less than 5 mm                                                                length of tape                                                                        --                      --                                            20 mm or more                                                                 binder                                                                        kind    urea resin  phenol resin                                                                              urea resin                                    amount (parts                                                                         15    25    15    25    15    25                                      by weight)                                                                    panel thickness                                                                       20 25 20 25 20 25 20 25 20 25 20 25                                   (mm)                                                                          strength                                                                      characteristics                                                               bending 65.1                                                                             51.0                                                                             81.8                                                                             69.2                                                                             64.0                                                                             51.6                                                                             66.8                                                                             59.3                                                                             87.2                                                                             64.0                                                                             98.3                                                                             82.6                                 strength.sup.1)                                                               (kgf/cm.sup.2)                                                                bending 3.7                                                                              4.6                                                                              4.5                                                                              6.2                                                                              3.6                                                                              4.8                                                                              4.2                                                                              5.3                                                                              4.9                                                                              6.8                                                                              5.9                                                                              7.5                                  rigidity.sup.2)                                                               (× 10.sup.5 kgf · cm.sup.2)                                    concrete                                                                      placing test.sup.3)                                                           maximum 2.7                                                                              2.0                                                                              2.2                                                                              1.7                                                                              2.8                                                                              2.2                                                                              2.3                                                                              1.9                                                                              2.0                                                                              1.6                                                                              1.7                                                                              1.3                                  deflection.sup.2)                                                             (mm)                                                                          evaluation of                                                                         □                                                                     ∘                                                                    □                                                                     ∘                                                                    □                                                                     □                                                                     □                                                                     ∘                                                                    ∘                                                                    ∘                                                                    ∘                                                                    ∘                        deflection.sup.4)                                                             __________________________________________________________________________     .sup.1) bending strength test using particle board (JIS A 5908)               .sup.2) panel width: 910 mm                                                   .sup.3) gap between battens: 200 mm                                           placing rate: 20 m/h                                                          placing height: 3.6 m                                                         specification of placing concrete: plain concrete, slump (21 cm), maximum     size of coarse aggregate (20 mm)                                              .sup.4) maxmimum deflection                                                   2.0 mm or less:                                                               2.0-3.0 mm:                                                                   3.0 mm or more: X                                                        

    __________________________________________________________________________    Inventive and                                                                 Comparative                                                                   Examples Inv. Ex. 7                                                                          Inv. Ex. 8                                                                          Comp. Ex. 1                                                                         Comp. Ex. 2                                                                         Comp. Ex. 3                                                                         Comp. Ex. 4                            __________________________________________________________________________    mixing ratio                                                                  magnetic tape                                                                 length of tape                                                                         70 parts by weight                                                                        30    50    70    conventional                           5-20 mm                                frame panel                            length of tape                                                                         30 parts by weight                                                                        70    30    30    using synthetic                        less than 5 mm                         resin foam                             length of tape                                                                         --          --    20    --                                           binder                                                                        kind     phenol resin                                                                              urea resin                                               amount (parts                                                                          15    25    25    25    10                                           by weight)                                                                    panel thickness                                                                        20 25 20 25 20 25 20 25 20 25 25 30                                  (mm)                                                                          strength                                                                      characteristics                                                               bending  85.8                                                                             67.1                                                                             95.6                                                                             72.3                                                                             47.3                                                                             35.9                                                                             34.9                                                                             23.8                                                                             19.6                                                                             15.8                                                                             26.2                                                                             19.1                                strength.sup.1)                                                               (kgf/cm.sup.2)                                                                bending  4.9                                                                              6.0                                                                              5.6                                                                              7.7                                                                              2.7                                                                              3.3                                                                              1.9                                                                              2.4                                                                              1.3                                                                              1.5                                                                              1.5                                                                              1.9                                 rigidity.sup.2)                                                               (× 10.sup.-5 kgf · cm.sup.2)                                   concrete                                                                      placing test.sup.3)                                                           maximum  2.0                                                                              1.6                                                                              1.8                                                                              1.5                                                                              3.9                                                                              3.2                                                                              4.6                                                                              4.1                                                                              6.4                                                                              5.7                                                                              5.3                                                                              4.7                                 deflection.sup.2)                                                             (mm)                                                                          evaluation of                                                                          ∘                                                                    ∘                                                                    ∘                                                                    ∘                                                                    X  X  X  X  X  X  X  X                                   deflection.sup.4)                                                             __________________________________________________________________________     .sup.1) bending strength test using particle board (JIS A 5908)               .sup.2) panel width: 910 mm                                                   .sup.3) gap between battens: 200 mm                                           placing rate: 20 m/h                                                          placing height: 3.6 m                                                         specification of placing concrete: plain concrete, slump (21 cm), maximum     size of coarse aggregate (20 mm)                                              .sup.4) maximum deflection                                                    2.0 mm or less:                                                               2.0-3.0 mm:                                                                   3.0 mm or more: X                                                        

The heat-insulating panel using contracted pieces of magnetic tapesaccording to the present invention is large in bending strength andbending rigidity, excellent in dimensional stability and small indeflection, and thereby it is usable as a panel serving also as aconcrete frame used in the construction of a building which is formed ofsteelframe reinforced concrete or reinforced concrete. Since theobtained panel has small spaces formed by contracted pieces of magnetictapes inside the board, it absorbs electromagnetic wave and shieldselectrostatic fields, in addition to its sound absorption andheat-insulation properties.

We claim:
 1. A method of manufacturing a heat-insulating panel servingas a concrete frame comprising the steps of:cutting or shreddingmagnetic tapes, such as video tapes or cassette tapes, in lengths of 20mm or less; heating said cut or shredded pieces of magnetic tapes at atemperature from 100° to 200° C., thereby obtaining curled contractedpieces of magnetic tapes; adding a thermosetting resin binder to saidcurled contracted pieces of magnetic tapes; and compression-molding saidcurled contracted pieces of magnetic tapes mixed with said binder at atemperature from 100° to 200° C.
 2. A method of manufacturing aheat-insulating panel serving as a concrete frame comprising the stepsof:preparing contracted pieces having lengths of 20 mm or less ofmagnetic tapes, such as video tapes or cassette tapes, said cut orshredded pieces containing those having lengths from 5 to 20 mm in anamount of 50% or more on the basis of the total tape weight; adding 10to 50 parts by weight of a thermosetting resin binder to 100 parts byweight of said contracted pieces of magnetic tapes, said bindercomprising a material capable of becoming hard and molded by heating, atleast one selected from the group consisting of phenol resin, urearesin, polyester resin, polyurethane resin, epoxy resin or melamineresin; and compression-molding said contracted pieces of magnetic tapesadded with said binder under a pressure from 2 to 20 kgf/cm² at atemperature from 100° to 200° C.